TRPM8: The Cold and Menthol Receptor

Excerpt

Our sensory systems are able to detect subtle changes in ambient temperature, due to the coordinated efforts of thermosensory neurons. At the level of the primary afferent nerve, the site at which thermal stimuli are converted into neuronal activity, temperature-sensitive members of the TRP channel family are found. Remarkably, the range of temperatures that these channels respond to covers the entire perceived temperature spectrum, from warm to painfully hot, from pleasingly cool to excruciatingly cold [1]. Moreover, many of these channels are receptors for ligands that elicit distinct psychophysical sensations, such as the heat associated with capsaicin and the cold felt with menthol. The latter of these was influential in the discovery of the first TRP channel shown to be responsive to temperatures in the cold range (<30°C), TRPM8, a member of the melastatin TRP channel subfamily [2,3]. This chapter focuses on TRPM8, describing what was known about cold signaling before the channel was cloned, how TRPM8 was identified as a cold sensor, and what advances have been made in our understanding of the molecular logic for cold sensation since its identification.